Jet vs Snow 2023, with Reheat 

And how much fuel they consume in burner...

And that's a little one...

I watched an interview with a US military Skycrane pilot, where he said that thing can fly at 70 knots straight up. I thought that was impressive. True?

@@AgentJayZ That’s true. When the CH-54B set the time to climb record back in the day, they were ascending at about 70kts for the first 9000ft. But slowed down to around 55kts as they reached 30,000ft. 3000m in 1 min 22sec, and 9000m in 5 min 57sec. Unfortunately, it’s only good for about 104kts in forward flight, which makes for some long, slow ferry flights. 👎🏻

@@AgentJayZ Couldn't a CH-53 beat the Saturn rocket to 10,000ft?

That sounds like a job for Calculon, er calculus. I didn't make it through calculus, otherwise I would have been an engineer, back when I thought I wanted to be one.

@@AgentJayZ you would be surprised, there are many engineers i work with that dont do the calculonian part of the work and just by experience do things, its not jet engines but when calculating pipe networks imo its important to do that caculonation stuff in some other parts its just filling for delivering a project to a customer, greetings from venezuela love your videos

Got a playlist for you, called the J79 Turbojet Engine.

@@AgentJayZ so . why did you test this engine for almost 16 years ? experiments ?

I have a playlist of the test runs of the many dozens of J79s we have worked on over the years... all for your enjoyment. How you could assume it was all the same engine is something I am unable to understand. You have impressed me with your powers.

The start cart makes about 90Hp, and it slams a 130dB meter, before the J79 ( roughly 15,000 Hp without reheat) even starts moving. My estimate of the SPL in reheat is over 160.

Many J79 afterburner test runs on this channel

@@AgentJayZ Yes sir, and I have seen them all.

I know there are various models of the Olympus. We have several industrial versions. I f you can get me part numbers, I can check to see if we have any matches. We do have a 591, but you have to accept the whole thing...

@@AgentJayZ My apologies for not picking this up sooner, AgentJayZ. I'll reply privately and include a photo, which may interest you.

I don't know what that is, but this is real.

My "other" snowblower is a GE-J79 😸

During the time I was a member of the in-service engineering support team at R-R Bristol for the Olympus 593, I was a regular visitor to Rolls-Royce's LHR office , which was at Hatton Cross, near the SE corner of the airport. I recall one winter evening, I was going back to my car on a winter evening just as Concorde was taking off from runway 27L The the noise level set off a large number of car alarms on the nearby off-airport car parks.

Twelve gallons per hour? Methinks you may have your units confused. The turbine engine in this video burns 38 gallons per minute. Add another fifty to that in afterburner. Yes, almost ninety gallons per minute at max roar. I spelled it out so there can be no doubt... 300L per minute when in the massively inefficient reheat, afterburner, post combustion. Over 9 tons of thrust, enough to push a Starfighter over Mach 2. Faster than an F-22. Oh, yeah!

@@AgentJayZin Australia we use them to put out fires in underground coal mines , they call it a gag

2M Btu/h is around 585 kWh A diesel generator that produces 600kWh of electric power uses about 40 gallons per h of fuel, so I think is perfectly reasonable for a jet engine that has a heat output of around 2M Btu/h to use about 12 gal/h of fuel. A very tiny jet engine tho.

We have three: Yellow leaky Green broken White working great

I have not seen a jet with an afterburner that is not capable of supersonic speed. The afterburner is

I think some really modern fighters, like the -35, the -22, the Typhoon and a couple others, can fly sustained supersonic without using reheat. Otherwise, you need to burn a lot of gas to go that fast.

Yes. Fixed it. I was trying to avoid using the word supercruise, for some reason.

There is a small transient increase in jet pipe pressure, but it is quickly adjusted for by the variable nozzle. None of the parts of the basic engine are different from a non-AB equipped J79.

Cracks are rare. It would be stupid and irresponsible to run an engine with cracks anywhere. We replace a part or repair it we find a crack. So I'm calling a no.

I gotta agree with Jay on this one. Old timer was pulling your leg. Even if you did need to run a cracked engine due to some urgent military situation, you'd stop drill the cracks with a drill, because you have no way to know whether the crack will grow before the magic pencil dots work their magic.

I got a fever. And the only remedy is more afterburner. 😂

There is a very small transient increase in jet pipe temp as the afterburner is lit, and this causes a few degrees increase in EGT, which is measured well before the AB section. This causes a tiny reduction in fuel flow for a few seconds. For all practical purposes, everything happening in the afterburner is after the engine, and has no real effect on it. If the variable nozzle did not open up in AB, then the jet pipe pressure would go up, and EGT would rise, causing the main fuel control to reduce fuel, which would reduce rpm, which would really mess up AB fuel, and probably stop it, which is good, because without the nozzle opening, the AB would just burn off the back of the engine...

Afterburner fuel flow is fully progressive from min to max. Exhaust gas speed is complicated, but in AB it is Mach 1 at the narrowest point of the converging/diverging nozzle. There is a component called the Nozzle Area Controller, which works in conjunction with the main fuel control and the AB fuel control, and the temperature amplifier to determine exhaust nozzle area. It can also be influenced by manual controls in the cockpit.

Thanks for that informative answer it makes sense and now I know!@@AgentJayZ

In my AB playlist, there's a vid showing a non-functioning torch igniter. A huge fog of unlit fuel out the back...

No. Because there is no actual flame downstream of the turbine. The hot gas just vaporises the injected fuel. One method of reheat ignition (and I'm using the term advisedly, because I'm referring to a Rolls-Royce engine) was to inject a slug of fuel into the combustion chamber (NOT combustor as I'm referring to a Rolls-Royce engine). This caused a 'hot streak' of flame to go through the turbine and ignite the fuel in the jet pipe.

The whole point of the turbine is to extract energy from the high pressure exhaust, by expanding and cooling it to extract mechanical work - there's hot and there's not so hot.

He's doing The Challenge. It's perfectly safe to be at the edge of the door, and look at the engine in full AB, as long as you have double hearing protection, and don't spend much time there. But nobody can do it. There is no actual exhaust or wind directed at you, only sound at unmeasurably high levels. You body will not let you do it. You decide to take a look, but the body says no way! We've all tried it, and so far nobody has succeeded. You know how, when you have earplugs in, your own voice inside your skull is much louder? Well, even from where I am recording the video, at full engine power, you can not hear yourself, even if you scream as loud as you can.

@@AgentJayZ Wow! That sounds like such a surreal experience.

The exhaust of the AB is supersonic, so the diverging part of the overall nozzle shape allows the further expansion of the gases once they leave the converging part... to push against that divergence. Supersonic aerodynamics are almost exactly the opposite of subsonic. Magic, I guess. The variable jet nozzle changes from a convergent to a con-di when the AB is lit. In my vid called "Books!" you'll find some better explanations. Also visit NASA's website, and search for jet nozzle.

What many people who haven't lived and breathed jet engines don't understand is this: the convergent final nozzle of a jet engine actually produces a rearward load on the rest of the engine. In afterburner, the convergent-divergent nozzle actually reduces the rearward load on the rest of the engine, which, as AgentJayZ has explained, does nothing different when the afterburner lights up. With a reduced rearward load from the con-di nozzle, the thrust of the engine is increased.

The jet thrust just past the turbine blades is low-subsonic. And the "squeeze" effect acts to accelerate it to high subsonic velocities. Allowing useful thrust at higher speed. It also develops more thrust than without a nozzle, because it accelerates the mass flow to a higher velocity creating an equal and opposite reaction to the mass-acceleration. When the afterburner is engaged, it burns additional fuel, along with oxygen rich air that comes around the outside of the engine, often used for cooling, and this generates additional pressure when "choked". A choke occurs when the additional pressure creates additional velocity and the airflow is accelerated to supersonic velocities in a nozzle throat. This choke is a supersonic shock wave that prevents more than a finite amount of air mass to travel thru that choked area. From this choked area having a terminal standing shockwave, the way to accelerate the flow above the sonic limit is not to compress it further, but to expand it. A De Laval convergent/divergent nozzle does just this. It was originally used to convert steam pressure into supersonic flow to turn primitive steam turbines. And is still used to this day in some electric power-plants. Also rocket nozzles. And anywhere a rocket effect is developed, e.g. afterburner.

Excellent question! We actually ran the start cart (90HP) inside the test cell one winter day, with doors closed. We went from -20C to +30 in about 15 seconds. If the J79 is the same core as an LM1500 (15,000 HP), and the reheat system burns 200% more fuel than the core... well. If we tried, the J79 would blow the door off long before it even got to full speed, which it needs to be at to enable reheat. ... reason for failure of experiment: destruction of building.

@@AgentJayZ Awesome! I'll keep an eye out for my next shop heater!

Core lock is not due to a design defect. When clearances are real snug in order to increase efficiency, and if the cases cool faster than the rotor after shutdown, parts touch and resist moving. Modern airliner engines are built with extremely small blade clearances. These engines need to be operated very carefully. The NTSB report seems to say that the pilots were playing with the aircraft, and were unaware that they were taking the aircraft and its engines outside their anticipated use. Ignoring the stall warnings and trying to maintain 41,000 ft caused the aircraft to slow way down. I'm not sure what caused the engines to flame out, but when they did, they were exposed to extremely cold airflow. The pilots did not immediately try to increase speed to windmill start, and during that time, the extreme cold caused core lock which was more sever than what would be caused at expected operating altitudes. They had to do a have a dozen inappropriate things to have it all add up to a crash. Of course in hindsight, it seems like it could have been so easily avoided.

About 15,000 Hp equivalent at military. I can't make an estimate of Hp in reheat, but it takes thrust from about 11,000lbs to about 18,000 lbs.

@@AgentJayZ any estimate of exhaust velocity in full reheat?

@@ShuRugal The exhaust velocity is supersonic because it's downstream of the convergent-divergent nozzle, where the velocity is at the speed of sound at the throat of the nozzle, and is then accelerated to supersonic speed in the divergent section of the nozzle. However, it's supersonic relative to the local gas temperature, and the speed of sound is proportional to the square root of the absolute temperature of the gas. Without knowing what that temperature is, I can't give you an approximate value for the exhaust velocity. Nevertheless, it will be greater than the maximum speed of (eg) an F-104 Starfighter or an F-4 Phantom, because the exhaust velocity must always be greater than the speed of the aircraft. Something called the Froude Equation applies: it simply shows that, if the jet velocity equals the forward velocity of the aircraft, there is no momentum change and there can be no propulsive thrust.

I could not explain it as well. TheF-104 was a Mach 2 + aircraft...

@@grahamj9101 Doesn't the propulsive efficiency raise drastically as the exhaust velocity nears the aircraft velocity?

I'll bet you a paycheck there's no comparison. All pulsejets I know about are toys, except the original V1, and I have not heard one of those. But you can not use a video to estimate the noise. Come on up and witness a test.

@@AgentJayZ I'd visit if I wasn't living 4000 miles away. We have some crazy people in Sweden racing on a frozen lake and one of the teams has built a pulsjet powered snow mobile. The engine performance is similar to the one on the V1. Of course it is a lot smaller than a J79 with maybe 3 % of the thrust but I meant more of a qualitative difference between pulses and continuous. Anyway watch?v=gquQxXUelfU at 14.30 they talk about the construction and a couple of minutes later they light up.

Yeah, nope. We ran for about 40 min. Several hundred gallons. Nope, not even close to a "storm". Meh.

@@AgentJayZ G'day JayZed, Those Several hundred gallons..., Would they be Real honest all growed-up Imperial Gallons, comprising 4.546 litres at per each...? Or were they those cut down Short-changed "US Gallons"..., which are Only 3.85 Litres...? The difference Matters. Many Aeroplanes have been known to run Tank Dry before arriving at their intended destination, due to people having Sold the Aircrew US "gallons", When they thought they were buying Actual real full-sized Imperial GALLONS... ! And, of course every Litre of Refined Fossil Fuel Emerges as Something like 2.3 Kg of CO-2 for burnt LPG, 2.5 Kg for Petrol, 2.6 Kg for Diesel, & 2.7 Kg for a litre of Kerosene. More Energy Density equals more CO-2 in the products of combustion. So if this test used 300 US gallons of LPG then it Pumped 2,656.5 Kg of Fossil Carbon into the Sky...; but if they were full-sized (non-Trumpified) Gallons, then it would have been 3,136.74 Kg of CO-2. 480.24 Kg difference, almost half a ton. And that roughly 3 Tons of Shit you Injected into the Sky will take 25 years to Finish achieving 95% of the Atmospheric Global Warming which it WILL Cause... So..., Apparently, EITHER You do not "Get" SCIENCE, and everything you do Is mere Monkey-see/Monkey-do type Rote, Parrot-fashion replication of the (OCD) Procedures - as taught in the textbook - all done by the numbers, technically proficient but guided by ZERO actual Comprehension of the Reality of the Principle of Cause & Effect... OR, You do not think that Kanadia had quite Enough Bushfires last Summer...; so the better to Satisfy the nostalgic Whims of some old Wannabe Jet-Pilots, you're literally Ready to Burn the World down - For Payment, Wages, Hire, Reward, and Apparently The Sheer bloody FUN of Squandering all that Energy, So very Fast.... Regardless of the Consequences. My road registered Electric Motorcycle Arrived a couple of weeks ago. $8,000 registered & delivered (630 km out of Sydney) $10,000 for the 3 Kw/Hr-day Solar Setup to recharge it, $4,000 for a Shed to keep it in, $4,000 for an eChainsaw, eBrushcutter & eLeafblower to round out the Project - with $500 for a Skid-Lid, Jacket & Gloves. That all should save me from burning 650 litres of Petrol Per Year... Because I Actually Give a Shit...(!). About stuff which Matters. And, due to the Skull fracture at age 14 After which I never ever learned anything new in a Mathematics Classroom... I figured all that out with Simple Arithmetic - and a 4-function Calculator built by Canon, in 1975... No "Calculus" involved (!). I really wish you would shut up that Workshop of yours, take early retirement ; And STOP SHITTING IN THE SKY...! Regardless of who Wants to pay you To Continue Nest-fouling, for your "Career". Generations yet unborn Would clap and cheer To hear That you had woken up to yourself To the point of Choosing to Stop making their Lives Un-liveable, For the fun of Burning Fuel in old Obsolete Turbine Engines.... Just(ifiably ?) sayin', Clean up your ACT... Get REAL, Please....? Such is life, Have a good one... Stay safe. ;-p Ciao !

The founder of S&S Turbine Services lives here. All of the other companies are offshoots of S&S.

These are a slightly modified reproduction of a -17, used in a particular combat aircraft that is not a Phantom II.

It's step 144-d in the global fuel conspiracy coverup, that you are eligible to join by watching my videos. Think wisely, because you can never leave once you sign up. Actually the computer has four channels to monitor four vibe sensors. On most tests, including this one, we are using three actual probes. Most aircraft monitor the engine vibration with one sensor per engine. Sometimes, an unconnected sensor lead will show erratic numbers on the screen, because of what, static electricity?

Different reasons, both relating to the mysterious magic of airflow. The Vulcan howl appears to me to be coming from the engine inlet ducts, which are part of the airframe. The older J79s had shorter exhaust nozzle segments, sometimes called petals or turkey feathers. Those early nozzles would act like a whistle at some part throttle settings. Later models of the J79 have an exhaust nozzle with longer petals, and there is no whistling howl. I think in both cases, the noise is caused by the air screaming in protest to what it is being subjected to.

@@AgentJayZ TKS! Mestre!

Implosion

The oxygen and nitrogen is the fuel. U really think those flimsy wings carry tons of fuel. Liquid fuel is the air

The gas turbine engine uses about 20% of the air that flows into it for combustion. About 80% is used for cooling. After all that leaves the engine, more fuel can be used for reheating it. Oh, and LAMethWitch is very kind for listing his/her educational history in her/his username.

LOL thanks J.. enjoy ur vids. just where are the fuel tanks ??? i wana see a 747 fill up.. when u fill up a car the nozzle points down with the fue flow why aircraft fill up with large air pipes it doesnt make sense @@AgentJayZ

If you go look at a 747, you will see a huge bulge right at the wing roots. You could park a couple city buses in there. That's the centre-wing fuel tank. Holds over 50 tons of fuel. Then look at the wings. you could stand up inside them. They have sealed off areas that hold about 40 tons each. Your homework is to find out the fuel consumption at cruise of a 747 engine, multiply it by 4, and see how many hours you come up with. That time multiplied by 800km/hr should give you the max range of the plane.

They are all very descriptive terms. The first time I heard the term "post combustion" it made me smile.

Doesn't the algorithm need seven or more words?

@@manifold1476 🤷🏼‍♂️

It is a bit redneck, but the guy who set up the computers is the guy on the throttle. The screens show the name of the variable, but not the actual units. This is not a customer item, this is the inner workings, so please don't insult us.

@@AgentJayZ sorry, didn't mean it as an insult. Internet comments remove all context. I just worry when I see things like that. So many accidents happen because someone assumed A unit but B units should have actually been used. There was a passenger fight that ran out of fuel because of that issue.

Canadians can easily switch back and forth between things like miles and kilometers, they don't need units, they just know

Yeah. The weather is in C, but we cook in F.